Effect of Carbon Nanostructures on the Cell Growth of Desmodesmus armatus Microalgae through Oxidative Stress

The wide practical application of carbon nanomaterials (CNM) is limited by their potential ecological toxicity, various aspects of which remain debatable. This work assesses the effect of graphene oxide (GO) and multi-walled carbon nanotubes (MWCNTs) on the growth, viability, oxidative stress, and content of photosynthetic pigments in the cells of a common microalga of the genus Desmodesmus. The study shows differences in the effects of different carbon nanomaterials at the same concentrations. Thus, GO does not have a negative effect on the viability and cell growth of the microalga Desmodesmus armatus with the exception of an increase in the level of oxidative stress, which ultimately affects growth of the culture. At the same time, when MWCNTs are added at concentrations of 100 and 1000 μg/L, a significant decrease in the growth of the cell number is recorded already on the 7th day of the experiment, with the effect maintained at the end of the experiment (14th day). At the same concentrations, a significantly higher level of oxidative stress is observed on the 14th day of the experiment. The analyzed CNMs do not have a reliable effect on the content of photosynthetic pigments. Thus, in the studied concentrations, GO turns out to be practically safe for the studied microalgae, unlike MWCNTs, which show noticeable toxicity. This can be taken into account in the future when developing practical applications for such CNMs, and can also be used in environmental regulation of their content in the environment.